Messages in this thread | | | Date | Fri, 27 Jan 2006 01:18:07 +0100 | From | Ingo Molnar <> | Subject | [lock validator] net/ipv4/fib_hash.c: illegal {enabled-softirqs} -> {used-in-softirq} usage? |
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the lock validator i'm working on found another item:
============================ [ BUG: illegal lock usage! ] ---------------------------- illegal {enabled-softirqs} -> {used-in-softirq} usage. hackbench/8407 [HC0[0]:SC1[2]:HE1:SE0] takes: {&state[i].lock} [<c0bf7d08>] wrandom_flush+0x2a/0xb3 {enabled-softirqs} state was registered at: [<c0befc33>] fn_hash_insert+0x565/0x5c3 hardirqs last enabled at: [<c0d29a36>] _spin_unlock_irq+0xd/0x10 softirqs last enabled at: [<c012d0a0>] irq_exit+0x36/0x38 other info that might help us debug this: locks held by hackbench/8407: <none> stack backtrace: [<c0103e86>] show_trace+0xd/0xf [<c0103e9d>] dump_stack+0x15/0x17 [<c013eb40>] print_usage_bug+0x16d/0x177 [<c013f130>] mark_lock+0xe3/0x248 [<c013f65d>] debug_lock_chain+0x3c8/0xb1d [<c013fde3>] debug_lock_chain_spin+0x31/0x48 [<c0410c4e>] _raw_spin_lock+0x34/0x7f [<c0d298fd>] _spin_lock+0x8/0xa [<c0bf7d08>] wrandom_flush+0x2a/0xb3 [<c0bc3738>] rt_cache_flush+0x3f/0xd8 [<c0bc3843>] rt_secret_rebuild+0x11/0x26 [<c0131165>] run_timer_softirq+0x143/0x19e [<c012d384>] __do_softirq+0x84/0xff [<c0104d76>] do_softirq+0x52/0xbb ======================= [<c012d0a0>] irq_exit+0x36/0x38 [<c0118809>] smp_apic_timer_interrupt+0x4e/0x51 [<c010376f>] apic_timer_interrupt+0x27/0x2c [<c01670b2>] kmem_cache_alloc+0x28/0xa6 [<c0b80be6>] __alloc_skb+0x25/0xee [<c0b7f144>] sock_alloc_send_skb+0x5d/0x192 [<c0c29bdf>] unix_stream_sendmsg+0x131/0x33f [<c0b7e30a>] do_sock_write+0xbd/0xc6 [<c0b7e441>] sock_aio_write+0x56/0x64 [<c016a9a4>] do_sync_write+0xb1/0xe6 [<c016adf0>] vfs_write+0xbd/0x155 [<c016b657>] sys_write+0x3b/0x60 [<c0102c25>] syscall_call+0x7/0xb
the culprit seems to be:
(gdb) list *0xc0befc33 0xc0befc33 is in fn_hash_insert (net/ipv4/fib_hash.c:527). 522 list_add_tail(&new_fa->fa_list, 523 (fa ? &fa->fa_list : &f->fn_alias)); 524 fib_hash_genid++; 525 write_unlock_bh(&fib_hash_lock); 526 527 if (new_f) 528 fz->fz_nent++; 529 rt_cache_flush(-1); 530 531 rtmsg_fib(RTM_NEWROUTE, key, new_fa, z, tb->tb_id, n, req); (gdb)
which enabled softirqs with {&state[i].lock} still held. If the rt_secret_rebuild() would hit that codepath at that point then it could cause a deadlock, right?
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